Treatment of oil wells



2 sheets-shet 1 J. E. MUNNA TREATMENT OF OIL WELLS Filed-May 19. 1941INVENToR `lune 18, 1946.

4, f .///vl INVENTOR 2 Sheets-Sheet 2 J. E. MUNN TREATMENT OF OIL WELLSvFiled May 19, 1941 June 18,1946?.

P'atented June 18,

UNITED STATES PATENT oI-FlcI 'y John E. Munn, Bellevue, Pa., assigner toChemical Service Company, Pittsburgh, Pa., a partnei-ship comprisingTheodore Schleid, Anita H. Munn, and John E. Munn Application May 19,1941, Serial No. 394,101

1 This invention pertains to the production of petroleum from wells, andrelates particularly to the reduction or'elimination of water frompetroleum producing wells. e

In many cases new wells which are driven into oil-bearing sands orstratum produce a relatively large volume of water from the beginning ofthe operation of the well. In other cases wells which have been inproduction for a period of time gradually begin to produce water and asthe operation of the well continues the water ows in an increasingamount until it mayI in some cases, entirely supplant the production ofoil. The present invention is applicableto the drilling of new wellswhere it-is anticipated that water may be encountered and it' isalsoapplicable to the correction of existing wells which are now producing aconsiderable volume of water.

y In the oil ilelds where water is-encountered the' oil-producing sandor stratum is often immediately above a stratum containing water. Thewell is drilled into the sand far enough to produce oil but it is notdrilled through the oil-bearing sand into the water.

In the ca s'e of the drilling of a new well, the operation of thedrilling tool up and down in the bottom of the well or the head pressureof water.

or drilling mud in the well drives water which may be in the welldownwardly through the forreduction in pressure due to the withdrawingof the oil from the producing sand creates an aspir ating effect andgradually causes the Water level immediately under the well to rise andat the same time capillaries are gradually opened up from thezoneimmediately under the bottom of the well downwardly toward thewater. These capillaries'increase in size and eventually the entire zonein the oil-producing stream immediately below the bottom of the wellbecomes full y of capillaries through which the water can flow directlyfrom the` water-bearing formation to the bottom of the well, andeventually a point may be 4 Claims. (Cl. 166-21) 2 reached where nothingbut water is pumped by the well. e

According to the present invention it is contemplated that a iluid beintroduced into the well which will -displace'the water in thecapillaries. ,or channels and which is heavier than the water so as toforce the water downwardly out of the capillaries or channels away fromthe bottom of the well. After its introduction, the heavier fluid istrapped in the formation at the bottom of the well, preferably by aspecially constructed packer, where it remains as a barrier to thefurther flow of water into the well.

My invention may be more fully understood by reference to theaccompanying drawings in which- Figure 1 is a schematic viewrepresenting the lower portion of a well -at the time that it rst beginsto produce water in appreciable quantities;

Figure 2 is a similar View showing the growth of the channels throughwhich water enters the well;

h Figure 3 is a similar view showing the intro- `duction of a correctionpacker into the well and illustrating the discharge of the firstsolutibn into the formation at the bottom of the well; l

s Figure 4 is a View similar to Figure 3 after the introduction of thesecond solution, two diierent solutions being used in succession in thecorrection of existing wells;

Figure 5 is a transverse vertical section through a correction packerused for the introduction of iiuids into the well and for the subsequentoperation of the well;

Figure 5a is a horizontal section in substantially the plane of line5ft-5a of Figure 5;

Figure 6 is a schematic view generally similar l to Figure 1 showing thestage at which drilling is temporarily halted to take steps to preventthe opening of capillaries through the producing y Figure 8 is avertical section through oneform V `of production packer which is usedin new wells.

Referring first to Figure 1, 2 designates the well which extends downinto the oil-bearing sand or stratum 3.

producing sand and 5 designates the tubing through which oil iswithdrawn or pumped rfrom the bottom of the well. Under the oil-bearingsand 3 is a water-bearing formation or stratum 6.

4 is the well-casing which usually terminates at some point above theoil- 3 Whenthe well is vproducing oil ows laterally through theoil-bearing sand into the bottom of the well and is withdrawn or pumpedout of the well tubing 5. 'I'he oil flowing in from the sides and up thetubing creates a suction or aspirating effect at the bottom of the well,creat- "ing a zone of relatively lower pressure in the vicinity of thebottom of the well which causes the normal water level in the stratum 6to rise. At the same time channels or capillaries through which the oilpreviously entered the bottom of the well tend to open up from thebottom 'of the well in a zone of downwardly increasing area. eventuallycommunicating with the underlying water. In lFigure 1 the generalcharacter of these channels or capillaries at the time when the wellfirst begins to produce water in appreciable quantities isdiagrammatically illustrated. As shown in Figure 2, because the ow ofwater has become established an increasing number of passages from thebottom of the well tothe water level are created and eventually there isa zone generally in the form of a cone from the bottom of the Well downto the water-bearing stratum through which water is drawn into the well,in many cases to the complete exclusion of the oil.

In correcting a' well where such a condition exists, ya. speciallyconstructed packer is first entered into the bottom of the well and set.One form of packer suitable for this purpose is illustrated in Figure 5.The particular packer is the subject-matter of a copending applicationfiled by me, Serial No. 394,102. led May 19, 1941, (Patent Number2,367,733, dated January 23, 1945 in which the packer is more fullydescribed and claimed, and it will be described hereinafter only insofaras is necessaryfor an understand` ing of the present invention. Thepacker as shown in Figure has a main lower body portion 8 having anipple-like element 8 secured to the lower end thereof. Secured to thenipple elel ment 8 is a compressible oil resistant resilient packing-body I0. The body I0 is preferably formed of a specially preparedrubber or plastic, which has the resilient and elastic properties ofrubber but which is not affected by oil or chemical compounds used inthe treatment of the well. Rubber coated with a synthetic rubber such,for example, as that known under the trade-mark 'I'hioko may be employedfor this purpose. The packing I0 has a central passage II therein andthere is a coil spring I2 in this central .passage to prevent the holeIl from closing when pressure is put on the packing and it is expandedat the bottom of the well.

The upper part of the body 8 has a neck portion 8a of reduced diameterand screwed on to the above the lower terminal portion of the tube,

the .perforations preferably being in the form of narrow slots. Thisperforated portion of the tubing provides al screen through which oilmay flow after the well is againA put into operation. At the top of thetubing I8 is a conical body I4 about which are a series of radiallymovable slips I5 of a type commonly found in oil well packers.

faces to catch against the interior of the casing and hold the packeragainst upward movement. At the top of the body I4 is a collar- I8 and acompression spring I'I interposed between the collar I6 and a ring I8serves to exert longitudinal .pressure against the ring I8 for forcingthe slips I5 down over the conical surface of the body I4 for expandingthe slips into contact with the casing.

Passing down through the body I4 and through the tubing I3 is a welltube I9. This tube is shown in Figure 5 as being screwed into the upperend of the neck 8a of the body 8.

Contained within the. body 8 is a plug 20 having an upper chamber 2Itherein and having a central passage 22 therethrough with an upwardlyclosing ball check valve 23 in this passage.

The chamber 2| at the top of the .plug 20 has an internal thread whichis a left-hand thread and screwed into the chamber is a disk 24 having acompressible plug 25 at the center thereof. As shown in Figure 5a, thisdisk has a series of openings 26 therein around the center and it isprovided with two diagonally opposite upstanding pins 21. In the lowerend of the tubing I! is a crosspin 28 which extends between the two pins21 forming, in effect. a spline or wrench for turning the disk 24. Thearrangement is such that when the well tubing I9 is rotated in acounterclockwise direction so as to screw it up wardly out of the neck8a. of the body 8, the disk 24 will be turned, but because of the threadon the interior of the chamber 2l being a lefthand thread the disk willscrew down as the tubing screws up to force thesealing D lug 2l plugthis hole.

In the treating of the well the packer which has been describedis'attached to the lower end of the Well tubing and itis lowered intothe bottom of the well. Pressure on the well tubing causes the body I0of packing material to be expanded against the sides of the well. Whenthe compressed packing tends to re-expand by slightly lifting the welltube, it tends to lift the body l and the tubing I3 and the body I4. Theconical surface of the body immediately expands the slips or grips I5against the interior of the casing. thus setting the packer. so that thepacking I8 re`- mains permanently under compression. At this time thedisk 24 is in the position shown in Figure 5 and fluid may be introducedinto the well tubing. This uid will flow down the well tube through theholes 28 in the disc 24, through the hole 22. forcing the valve 28downwardly. The liquid may continue down through the packing I0 and bedischarged into the bottom of the well.

In the practice of the present invention I preferably first introduceinto the bottom of the well through this specially constructed packer aliquid whose function'is to enter the capillaries extending downwardlyfrom the bottom of the wall and decrease the surface tension of thewater in the area immediately below the bottom of the well. In Figure 3the shaded area designated generally at 30 indicates the diffusion ofthis first liquid through the zone at the bottom of the well. Numeroussubstances may be used for this purpose. Ordinary alcohol, for example,will mix with the water and decrease its surface tension. Variousindustrial soaps may be used, ,or a wetting agent, such as that soldunder the trade name of "Aerosol may be'employed. By the introduction ofa wetting agent into the bottom the members I5 having serrations ontheir outer 75 of a well to reduce surface tension of the water,

the water wm tend to drain more freely from the capillaries. As thewetting agent is introduced it will tend to now downwardly and spreadout lat-- erally, eventually permeating the conical zone extended fromthe bottomy of the well down to the normal water-level. The amount ofwetting agent to be introduced has to be determined from known factorsin the particular field in which the well is located. the amountdepending very largely, however, upon the depth of the oil-bearing sandand the calculated distance from the bottom of the well to the normalwater level. The fluid is introduced under pressure greater than thenormal pressure inv the well.

After the first fluid has been introduced, a second fluid is introducedin the same manner. This second fluid is a liquid which is heavier thanwater. 'Ihe fluid is preferably one which is a solvent for oil andwhich, while normally not readily miscible with water will, by reason ofthe wetwater, mix to some extent therewith. 'I'he fluid which ispreferably used is carbon tetrachloride, which substance is a solventfor petroleum vbut which is normally substantially insoluble in water.When the carbon tetrachloride is injected into ting agent which has beenintroduced into the the bottom of the well, it follows down thecapillaries toward the water-bearing stratum.` Because of its beingheavier than the water, it forces much of thel water down thesecapillaries out of the oil-bearing sand. Some of the water with thewetting agent in it will be forced upwardly into the sand around thebottom of the well. 'I'he action of the second fluid is diagrammaticallyillustrated in Figure 4 where the area 3| designates that zone throughwhich the second fluid has '6 well. All of the liquid that can enter thewell must flow into the well laterally in the zone above the packing I0.It enters the tubing Il through the slots therein and is then drawn orforced up into the well tubing. v

In the first short period of the operation of the well the water in thezone 30 will be withdrawn from the well. and after this water has beenwithdrawn the oil will flow laterally through the sand. One reason forthe original entry of the water into the well is that the oil in flowinginto the well and then up to the well tubing creates an aspiratingeffect or low pressure area imy mediately below the bottom of the welltending to raise the water level, and eventually draw the waterupthrough the oil-bearing sand into the- The provisionof a packingbottomof the well. I0 positively destroys this aspirating action. With thisinvention there is created a condition where. in the conical areaimmediately under the after produce water in any substantial quantitlesfor an indenite period of time.

This treatment of. the well is relatively inexpensive in that thechemicals used for the treatment are. relatively cheap and aside fromthe chemicals, the only additional equipment required isl the packer.

An important function of the packer'is Vits con- Y struction whichpennits the forcing of the liquid of carbon tetrachloride to be used hasto be de- 1 termined from the known facts about the well, including thedepth of the oil-bearing sand and the distance between the bottom ofthewell and the normal water level. Y

After the second fluid has been introduced,the -well is then ready to beput back into operation. The first step in putting the well back intooperation is to turn the well tubing I9 in a counterthe neck portion 8aof the body 8 at the bottom of the packer. 'Ihe turning of the tube inthis direction screws the disk 24 downwardly, forcing the plug 25against the top of the hole 22. 'I'he A check valve 23 forms onepositive seal against any each forming a checkagainst the other -toassure against the back flow lof fluid through the packer.

When the well tubing I9 has been unscrewed from the neck 8a of the body8 it is elevated a short distance above the body 8. After thetubdownwardly throughthe bottom of the well into the sand below thebottom and which positively seals the bottom of the well against anyflowing fluid upwardly through the packer.

In the drilling of new wells in formations where water is anticipated,the drilling is proceeded with asusual until the drilling toolapproaches relatively close to the oil-bearing sand. When the drillinghas approached within a predetermined distanceof say, fty feet of theoil-bearing sand, the drilling operation is stopped and as much of thewater as possible is bailed out of the bottom of the well. After thewell has been bailed as dry as possible, a considerable quantity ofliquid which is heavier than Water, preferably carbon tetrachloride, ispoured into the zwell, after which the drilling is continued. -Thusinstead of water being forced downwardly through the formations underthe impact of thedrilling tool. carbonl tetrachloride is forceddownwardly through these formations; When the oil-bearing sand iseventually reached and penetrated by the drilling tool. the capillariesare filled with carbon tetrachloride which is heavier than water andwhlchtends to prevent the rise of water upwardly through thecapillaries. Carbon tetrachloride also dissolves paramn deposits in theoildrilling operation is stopped and the carbon tetraing has been thusdisconnected and raised, the

pumping of the well may be started. The packer at the bottom of the wellprevents lany flow of liqbearing statum, thus enabling oil to flow morefreely into the well.

Referring to Figure 6, this ligure indicates the depth to which the wellis drilled, after which the chloride introduced into thel well 'whilethe dotted lines projecting downwardly from the well indicate the depthto which the well is to'be subsequently drilled. In thisgure the casingis desuid in a vertical direction directlyk up into .the ignat'ed 34.After the well has been drilled toits :,soasss 7 full depth, a packer isset in the bottom of the well to close the bottom of the well againstthe iow of fluid upwardly through it and prevent the aspirating effectheretofore described from drawing the water from the normal water levelinto the sand -in'the bottom of the well. One form of packer which maybe used for this purpose is shown in Figures '7 and 8, while mycopending application above referred to discloses another form of packerfor the same purpose. Referring to Figure 7, 35 designates the welltubing, and $8 designates generally the packer at the bottom of thetubing. This packer has a shell 31 which is perforated to permit theflow of oil laterally from the sand into the interior of the shell. Thewell tubing 3B extends down into the shell `and terminates above thebottom of the packer.. Carried at the bottom of the packer is a body 38of a resilient compressible material as. for example, synthetic rubber,or natural rubber coated with fThiokol. Under the weight of thesuperimposed column of tubing 35 the packingv 3l is expanded radiallyand compressed against the bottom of the well to eilectually seal thebottom of the well against any upow of fluids. The oil which ows throughthe perforated shell Il is. of course, drawn out through the tube 3l.Where the well flows under its own pressure I prefer to use a valve 38at the top of the well so as to partially restrict the flow of oilbecause by restricting the flow of oil a greater pressure is vmaintained'in the zone around the bottom of` direction.

The fluid which is heavier than water penetrates, as previouslyindicated, the water passages.

and capillaries in the oil producing stratum below the bottom of thewell. It diffuses through the capillariesin a downwardly spreading conewith-the bottom of the well at the apex of the cone and serves as ablanket over the underlying water, filling the capillaries andpreventing the water 'of this cone. definitely prevents 'the heavyliquid from being drawn back into the bottom of the well. Also, sincethe liquid is heavier than water, any suction will be more effective tomove the oil which is lighter than water, than to move the liquid whichis heavier than water, which is a further factor tending to prevent therapid removal of the heavy fluid.

While I have illustrated and described certain specific apparatus forthe practice of my invention and certain specific materials for use incarrying out my invention, it will be understood that various changesand modifications may be made, both in the apparatus and materials, andwithin the contemplation of my invention and the sco of the followingclaims. 1

I claim:

l. The method of treating oil wells in which water is present whichcomprises forcing a liquid capable of reducing the surface tension ofwater into the oil-producing stratum below the bottom of the well,thereafter introducing a second liquid consisting essentially of carbontetrachloride into the same portion of the stratum to displace the waterwhich has been treated with the first liquid, and thereafter sealing thebottom of the from rising. Being heavier than -the water, it will y actpositively to force the water back through4 the capillaries, spreadingout inl a conical pattern of downwardly increasing diameter. When the'treated well is subsequently being pumped the greatest suction is at thebottom of the well. This is due not only to the action of the pumpitself, but to the aspirating effect of the oil flowing laterallyinwardly. The packer, being at the apex well only below a given oilproducing level against the upiiow of liquid therethrough.

2. The method of correcting producing wells in which water is flowingwhich comprises forcing a wetting agent into the oli-producing stratumin the zone immediately below the bottom of the well, and then forcingcarbon tetrachloride into the same zone, and trapping the carbontetrachloride in said zone.

3. The method of correcting producing wells in which water is flowingwhich comprises forcing a wetting agent into the oil-producing stratumin the zone immediately below the bottom of the well, then forcingcarbon tetrachloride into the same zone, and thereafter sealing thebottom of the well against the direct upilow of fluid therethroughwhereby the carbon tetrachloride is trapped in the zone into which it isinjected.

4. A method of treating oil wells in which water is present whichcomprises forcing a liquid capable of reducing the surface tension ofwater through a tubing extending to the bottom of the well into the oilproducing stratum below the bot-4 tom of the well, said liquid -beingconfined to penetration of the portion of the stratum at the bottom ofthe well only, thereafter in the same manner introducing into the oilproducing stratum below the bottom of the well only a liquid consistingessentially of carbon tetrachloride, and then mechanically sealing thecarbon tetrachloride so introduced in the oil producing stratum belowthe bottom of the well.

f- JOHN E. MU'NN.

